KR101556486B1 - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

Provided is a nonaqueous electrolyte secondary battery which is excellent in internal and external stress and capable of increasing detection sensitivity of an increase in internal pressure at the time of overcharging without deteriorating battery performance such as battery capacity. The nonaqueous electrolyte secondary battery comprises a porous heat-resistant layer 24 disposed between a positive electrode 21, a negative electrode 22, a positive electrode 21 and a negative electrode 22 and including an insulating inorganic filler and a binder, A nonaqueous electrolyte added with an overcharge inhibitor which is decomposed at the time of overcharging to generate protons and a current cutoff mechanism which cuts off the charge when the internal pressure of the battery becomes higher than a predetermined value at the time of charging, At least a part of the filler is constituted by a proton conductive ceramic.

Description

[0001] NONAQUEOUS ELECTROLYTE SECONDARY BATTERY [0002]

The present invention relates to a nonaqueous electrolyte secondary battery.

A conventional non-aqueous electrolyte secondary battery such as a lithium ion secondary battery is roughly composed of a positive electrode, a negative electrode, a separator for insulating therebetween, and a nonaqueous electrolyte. As the separator, a porous resin film such as a polyolefin film is widely used.

In a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery, as a safety countermeasure for overcharging, there is a case where a current interrupting mechanism for shutting off charging when the internal pressure of the battery becomes higher than a predetermined value at the time of charging (for example, , Paragraph 0094 of Patent Document 1).

In Patent Document 1, in order to increase the detection sensitivity of the rise of the internal pressure, an overcharge preventing agent which decomposes at the time of overcharge to generate protons is added to the non-aqueous electrolyte. In this configuration, when the battery is overcharged, the overcharge preventing agent is decomposed to generate protons, and the protons are reduced at the negative electrode to generate hydrogen gas.

In Patent Document 1, biphenyls, alkylbenzenes, alkyl compounds substituted with two aromatic groups, fluorine atom-substituted aromatic compounds, and chlorine atom-substituted biphenyls are exemplified as overcharge inhibitors in the description of the prior art (Paragraphs 0009, 0011, 0014).

In claim 1 of Patent Document 1, at least one chlorine atom-substituted aromatic group selected from the group consisting of chlorine atom-substituted biphenyl, chlorine atom-substituted naphthalene, chlorine atom-substituted fluorene and chlorine atom- Compounds are illustrated.

However, in a non-aqueous electrolyte secondary battery using a porous resin film such as a polyolefin as a separator, when a stress is externally applied, the non-aqueous electrolyte is extruded from the separator, and as a result, ion conductivity of the separator is reduced, There is a possibility of deterioration (paragraph 0004 of Patent Document 2).

Patent Document 2 discloses a nonaqueous electrolyte secondary battery using a highly rigid porous heat-resistant layer (HRL layer) including an insulating inorganic filler and a binder in combination with a conventional resin separator or in combination with a conventional resin separator (Claim 5, Figs. 1 and 3).

As the insulating inorganic filler of the porous heat-resistant layer (HRL layer), at least one member selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, TiO ₂ and ZrO ₂ is used (claim 6).

Japanese Patent Application Laid-Open No. 2004-087168 Japanese Patent Application Laid-Open No. 2007-012598

Nonaqueous The overcharge inhibitor is added to the electrolyte, the battery internal pressure when a predetermined value or more Al ₂ O as described in Patent Document 2 for which the current blocking mechanism for blocking the filling with the non-aqueous electrolyte secondary battery _3, SiO ₂ at the time of charging, (HRL layer) comprising an insulating inorganic filler containing at least one member selected from the group consisting of MgO, TiO _2, and ZrO ₂ is used, the insulating inorganic filler is decomposed by over- There is a possibility that the hydrogen gas generated on the generated proton or negative electrode is adsorbed and the current interruption mechanism does not work well.

Since the above-mentioned insulating inorganic filler has a hydroxyl group on its surface, it adsorbs protons. In addition, the above-mentioned insulating inorganic filler may adsorb hydrogen by the catalytic effect.

When the addition amount of the overcharge preventing agent is increased in order to increase the detection sensitivity of the rise of the internal pressure and to increase the safety, the battery capacity tends to decrease, and the addition amount is limited.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a nonaqueous electrolyte secondary battery which is excellent in internal and external stress and capable of increasing detection sensitivity of an increase in internal pressure at the time of overcharging without deteriorating battery performance such as battery capacity It is aimed at.

In the nonaqueous electrolyte secondary battery of the present invention,

A porous heat-resistant layer (HRL (Heat Resistance Layer) layer) disposed between the positive electrode and the negative electrode and including an insulating inorganic filler and a binder, and an overcharge A nonaqueous electrolyte secondary battery comprising a nonaqueous electrolyte to which an inhibitor is added and a current interrupting mechanism for shutting off charging when the internal pressure of the battery reaches a predetermined value or higher during charging,

At least a part of the insulating inorganic filler of the porous heat-resistant layer (HRL layer) is constituted by a proton conductive ceramic.

According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery which is excellent in internal and external stresses and capable of enhancing detection sensitivity of an increase in internal pressure at the time of overcharging without deteriorating battery performance such as battery capacity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a general view schematically showing a configuration example of a nonaqueous electrolyte secondary battery according to the present invention. FIG.
2 is a partial cross-sectional view of the nonaqueous electrolyte secondary battery of FIG.

Hereinafter, the present invention will be described in detail.

In the nonaqueous electrolyte secondary battery of the present invention,

A nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a porous heat-resistant layer (HRL layer) disposed between the positive electrode and the negative electrode and including an insulating inorganic filler and a binder, A nonaqueous electrolyte secondary battery comprising an electrolyte and a current interrupting mechanism for interrupting charging when the internal pressure of the battery reaches a predetermined value or higher at the time of charging,

At least a part of the insulating inorganic filler of the porous heat-resistant layer (HRL layer) is constituted by a proton conductive ceramic.

Figs. 1 and 2 schematically show a configuration example of a nonaqueous electrolyte secondary battery. Fig. Fig. 1 is an overall view, and Fig. 2 is a partial cross-sectional view. All are diagrams.

The nonaqueous electrolyte secondary battery 1 shown in Fig. 1 is housed in the outer casing 11 with the laminate 20 shown in Fig. 2 and a nonaqueous electrolyte (not shown) to which an overcharge inhibitor is added.

The laminate 20 includes a positive electrode 21 coated with a particulate positive active material on a current collector, a negative electrode 22 coated with particulate negative active material on the current collector, a resin separator 23, Layer (HRL layer) 24 are laminated.

The porous heat-resistant layer (HRL layer) is used as a member for insulating between a positive electrode and a negative electrode in place of a resin separator widely used in the past or in combination with a widely used resin separator.

The position of the porous heat-resistant layer (HRL layer) 24 is not particularly limited as long as it is between the positive electrode 21 and the negative electrode 22. The surface of the positive electrode 21 and the surface of the negative electrode 22, Or on the surface of an electrode mixture layer (not shown) that is formed if necessary in order to integrate the positive electrode 21 and the negative electrode 22.

As shown in Fig. 1 of Patent Document 2 exemplified in the section of "Background Art", a pair of positive electrodes 21 and a negative electrode 22 are provided between a pair of positive and negative heat- (HRL layer) 24 may be interposed therebetween.

The nonaqueous electrolyte secondary battery 1 is provided with a current interrupting mechanism 13 for shutting off charging when the internal pressure of the battery becomes equal to or higher than a predetermined value at the time of charging in the external body 11. The location of the current interruption mechanism 13 is designed in accordance with the current interruption function.

In order to increase the detection sensitivity of the rise of the internal pressure, an overcharge preventing agent which decomposes at the time of overcharge to generate protons is added to the non-aqueous electrolyte. In this configuration, when the battery is overcharged, the overcharge protection agent in the non-aqueous electrolyte is decomposed to generate protons, and the protons are reduced at the negative electrode to generate hydrogen gas. The internal pressure of the cell rises due to the generation of the gas, and the current is cut off by the current interruption mechanism 13. [

As the current interruption mechanism 13, a known mechanism can be employed.

As the current interrupting mechanism 13, a structure for deforming by the rise of the battery internal pressure to turn off the contact of the charging current, an external circuit for detecting the battery internal pressure by the sensor and stopping the charging, An external circuit for stopping charging, and a structure deformed by an increase in the cell internal pressure to short circuit the positive electrode and the negative electrode.

For example, a structure or the like which is deformed due to an increase in the cell internal pressure to turn off the contact of the charging current is preferable because of its simple structure and high current blocking effect.

Two terminals (positive terminal and negative terminal) 12 for external connection are provided on the outer surface of the external body 11.

≪ Porous heat-resistant layer (HRL layer) >

Since the nonaqueous electrolyte secondary battery of the present invention includes the porous heat-resistant layer (HRL layer), it has excellent external and internal stress.

As described in the section entitled "Problems to be Solved by the Invention", when the overcharge preventing agent is added to the nonaqueous electrolyte, and when the internal pressure of the battery becomes equal to or higher than a predetermined value at the time of charging, the nonaqueous electrolyte 2 (HRL layer) comprising an insulating inorganic filler comprising at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, TiO ₂ and ZrO ₂ described in Patent Document 2, There is a possibility that the current blocking mechanism does not work well due to the adsorption of the hydrogen gas generated on the proton or the negative electrode generated by the decomposition of the overcharge preventing agent when the insulating inorganic filler overcharges.

Since the above-mentioned insulating inorganic filler has a hydroxyl group on its surface, it adsorbs protons. In addition, the above-mentioned insulating inorganic filler may adsorb hydrogen by the catalytic effect.

In the nonaqueous electrolyte secondary battery of the present invention, at least a part of the insulating inorganic filler constituting the porous heat-resistant layer (HRL layer) is constituted by a proton conductive ceramic.

In the above-described structure, the protons generated by the decomposition of the overcharge inhibitor during the overcharging are released even when they are adsorbed on the porous heat-resistant layer (HRL layer), and do not stay in the porous heat-resistant layer (HRL layer). In addition, the proton conductive ceramics described above are also low in hydrogen adsorption. In the present invention, since the adsorption of protons and hydrogen gas in the porous heat-resistant layer (HRL layer) is suppressed, the current interruption mechanism works well.

The present invention does not need to increase the amount of the overcharge inhibitor added, so that it is possible to increase the detection sensitivity of the rise of the internal pressure at the time of overcharging without deteriorating the battery performance such as the battery capacity.

Proton conductive ceramics have a higher electrical resistance than non-proton conductive ceramics. By using this, the insulating performance of the porous heat-resistant layer (HRL layer) is enhanced, and an effect that a short circuit can be prevented at a higher level is also obtained.

As the insulating inorganic filler used in the present invention, for example, at least a part of the surfaces of ceramic particles containing at least one kind of proton conductive ceramics and at least one kind of non-proton conductive ceramic particles are mixed with at least one kind of proton conductive ceramics And ceramic particles coated with ceramics.

In the porous heat-resistant layer (HRL layer), ion conductive pores are formed by the gaps between the insulating inorganic fillers in the particulate form.

In all of the above-mentioned ceramic particles, at least a part of the surface of the insulating inorganic filler is a proton conductive ceramic. In such a configuration, since the proton conductive ceramic is present on the wall surface of the ion conductive hole, the ion conductivity of the porous heat-resistant layer (HRL layer) is improved, which is preferable.

The proton conductive ceramics are not particularly limited as long as they have proton conductivity.

As the proton conductive ceramic, it is preferable to include at least one kind of metal oxide represented by the following formula (1).

≪ Formula 1 >

(Wherein A represents Ba and / or Sr, B represents Ce and / or Sr and C represents at least one kind of additive element, 0? X <1, a? 0)

As the metal oxide represented by Formula _{1, BaCeO 3, SrZrO 3,} SrCeO 3, BaZrO 3, there may be mentioned those as a host oxide and the like are added to a ceramic, and combinations of these optional ingredients.

It is particularly preferable that the proton conductive ceramic contains at least one kind of metal oxide represented by the following formula (1a).

<Formula 1a>

(Wherein A is Ba and / or Sr, B is Ce and / or Sr, C is Y and / or Yb, 0 &lt; x &lt;

It is preferable to add Y and / or Yb to BaCeO ₃ , SrZrO ₃ , SrCeO ₃ , or BaZrO ₃ to change the valence of Ce or Zr and consequently to improve the proton conductivity.

In the at least one metal oxide represented by the above formula (1a), the addition amount x of the additive element is particularly preferably 0.01 to 0.5.

If x is excessively small, the effect of addition of Y and / or Yb is not sufficiently manifested, and if it is too large, the additive elements are not solved well and there is a possibility of abnormal precipitation.

Examples of the non-proton conductive ceramics include Al ₂ O ₃ , SiO ₂ , MgO, TiO ₂ , ZrO ₂ , ceramics to which an optional component is added as a matrix oxide, and combinations thereof.

The method of coating at least part of the surface of the non-proton conductive ceramic particles with a ceramic containing at least one kind of proton conductive ceramics is not particularly limited.

For example, there can be mentioned a method of spraying a solution or a slurry containing the metal oxide precursor represented by the above formula (1) onto non-proton conductive ceramic particles, drying, and firing.

The precursor of the metal oxide is not particularly limited, and examples thereof include acetic acid salts of the constituent metals of the metal oxide.

An example of the covering method will be described by taking as an example the case where at least a part of the surface of the non-proton conductive ceramic particle is covered with BaCeO ₃ .

Ethylenediamine tetraacetic acid (EDTA) is dissolved in ammonia water, cerium acetate is added, ethylene glycol is added as a stabilizer, and the solution is dissolved by heating. Further, barium acetate is added, and the mixture is further heated to dissolve. The obtained precursor solution may be used as it is, or it may be concentrated to a slurry if necessary.

The concentration of the precursor in the solution or slurry of the precursor is not particularly limited, and is preferably 0.3 to 0.6 mol / L, for example.

The solution or slurry of the obtained precursor is sprayed onto the non-proton conductive ceramic particles, preferably dried at 100 to 150 占 폚, and preferably at 1000 to 1400 占 폚. As described above, at least a part of the surface of the non-proton conductive ceramic particle can be coated with BaCeO ₃ .

The thickness of the coating film is not particularly limited, and is preferably 0.5 to 1.0 占 퐉, for example.

If the thickness of the coating film is too small, the effect of covering can not be sufficiently manifested and if it is excessive, uniform coating becomes difficult.

The average particle diameter of the ceramic particles constituting the porous heat-resistant layer (HRL layer) is not particularly limited, and is preferably 0.3 to 4 mu m, for example. This range is preferable because a good porosity and good strength can be obtained for ion conduction (see paragraph 0034 of Patent Document 2).

As the binder constituting the porous heat-resistant layer (HRL layer), known ones can be used, and examples thereof include polyvinylidene fluoride (PVDF), modified acrylic rubber, and combinations thereof.

Generally, the binder absorbs and swells the non-aqueous electrolyte after the cell structure. Therefore, the amount of the binder to be added is preferably small. The above-mentioned polyvinylidene fluoride and acrylic rubber exhibit a binding effect even in a small amount, so that the addition amount can be reduced, which is preferable. The amount of the binder is not particularly limited, and it is preferable that the insulating filler can be bound well, and in order to suppress the swelling due to the absorption of the non-aqueous electrolyte, for example, it is preferably 0.3 to 8.5 mass% with respect to the insulating filler (Patent Document 2 See paragraph 0036).

The production method of the porous heat-resistant layer (HRL layer) is not particularly limited. The porous heat-resistant layer (HRL layer) can be produced, for example, by applying a mixture obtained by mixing an insulating filler, a binder and a dispersion medium to a surface of a positive electrode, a negative electrode, or a separator, and drying the mixture with far- have.

Since the non-aqueous electrolyte secondary battery of the present invention uses a porous heat-resistant layer (HRL layer) having high rigidity including an insulating inorganic filler and a binder, the non-aqueous electrolyte secondary cell has excellent external and internal stress.

As described in the section entitled "Problems to be Solved by the Invention", when the overcharge preventing agent is added to the non-aqueous electrolyte and when the internal pressure of the battery reaches a predetermined value or more during charging, (HRL layer) comprising an insulating inorganic filler comprising at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ , MgO, TiO ₂ and ZrO ₂ described in Patent Document 2 There is a possibility that the current blocking mechanism may not operate well due to adsorption of hydrogen gas generated on the proton or negative electrode generated by decomposition of the overcharge preventing agent when the insulating inorganic filler overcharges.

In addition, when the addition amount of the overcharge preventing agent is increased in order to increase the detection sensitivity of the rise of the internal pressure and increase the safety, the battery capacity tends to decrease, and the addition amount is limited.

In the present invention, at least a part of the insulating filler constituting the porous heat-resistant layer (HRL layer) is constituted by the proton conductive ceramic.

According to the present invention having such a constitution, it is possible to provide a non-aqueous electrolyte secondary battery which is excellent in internal and external stresses and can increase detection sensitivity of increase in internal pressure at the time of overcharging without deteriorating battery performance such as battery capacity.

Examples of the non-aqueous electrolyte secondary battery include a lithium ion secondary battery and the like. Hereinafter, the main components of the nonaqueous electrolyte secondary battery will be described using a lithium ion secondary battery as an example.

<Positive Electrode>

The positive electrode can be produced by applying a positive electrode active material to a positive electrode current collector such as an aluminum foil by a known method.

No particular limitation as positive electrode active material of the known, for example, _{LiCoO 2, LiMnO 2, LiMn 2} O 4, LiNiO 2, LiNi x Co (1-x) O 2 and _{LiNi x Co y Mn (1-} xy) O 2 , etc. And lithium-containing complex oxides.

For example, a dispersion agent such as N-methyl-2-pyrrolidone is used, and the above-described positive electrode active material, a conductive agent such as carbon powder, and a binder such as polyvinylidene fluoride (PVDF) And this slurry is coated on a positive electrode current collector such as an aluminum foil, dried, and pressed to obtain a positive electrode.

The amount of the positive electrode to be applied is not particularly limited and is preferably 1.5 to 15 mg / cm 2. If the application amount of the positive electrode is too small, uniform application is difficult, and if it is excessive, there is a fear of peeling off from the current collector.

<Negative electrode>

The negative electrode can be produced by applying a negative electrode active material to a negative electrode collector such as a copper foil by a known method.

The negative electrode active material is not particularly limited and preferably has a lithium intercalation capacity of 2.0 V or less based on Li / Li +. Examples of the negative electrode active material include carbon such as graphite, metal lithium, a lithium alloy, a transition metal oxide / transition metal nitride / transition metal sulfide capable of doping / dedoping lithium ions, and combinations thereof.

For example, a dispersing agent such as water is used, and the negative electrode active material, a binder such as modified styrene-butadiene copolymer latex and, if necessary, a thickening agent such as carboxymethyl cellulose Na salt (CMC) And the slurry is coated on a negative electrode current collector such as a copper foil, dried, and pressed to obtain a negative electrode.

The amount of the negative electrode to be applied is not particularly limited and is preferably 1.5 to 15 mg / cm 2. If the applied amount of the negative electrode is too small, it is difficult to uniformly apply the coating, and if it is excessive, there is a fear of peeling off from the current collector.

In a lithium ion secondary battery, a carbon material capable of intercalating and deintercalating lithium is widely used as a negative electrode active material. Particularly, highly crystalline carbon such as graphite is used as a negative electrode active material for most of commercially available lithium ion secondary batteries since it has properties such as a flat discharge potential, a high true density, and a good filling property. Therefore, graphite and the like are particularly preferable as the negative electrode active material.

<Non-aqueous electrolyte>

As the non-aqueous electrolyte, a known electrolyte may be used, and a non-aqueous electrolyte in a liquid, gel or solid state may be used.

For example, a mixed solvent of a high-keto carbonate solvent such as propylene carbonate or ethylene carbonate and a low-viscosity carbonate solvent such as diethyl carbonate, methyl ethyl carbonate or dimethyl carbonate A nonaqueous electrolyte solution in which a lithium-containing electrolyte is dissolved is preferably used.

As the mixed solvent, for example, a mixed solvent of ethylene carbonate (EC) / dimethyl carbonate (DMC) / ethyl methyl carbonate (EMC) is preferably used.

The lithium-containing electrolyte as, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, Li 2 SiF 6, LiOSO 2 C k F (2k + 1) ( integer of _{k = 1~8), LiPF n {} C k F ( _{2k + 1)} } _(6-n) (n is an integer of 1 to 5, k is an integer of 1 to 8), and combinations thereof.

As the overcharge preventing agent which decomposes to generate protons upon overcharging, known ones can be used. For example, the overcharge preventing agent described in Patent Document 1 exemplified in &quot; Background Art &quot;

In Patent Document 1, biphenyls, alkylbenzenes, alkyl compounds substituted with two aromatic groups, fluorine atom-substituted aromatic compounds, and chlorine atom-substituted biphenyls are exemplified as overcharge inhibitors in the description of the prior art (Paragraphs 0009, 0011, 0014).

In claim 1 of Patent Document 1, at least one chlorine atom-substituted aromatic group selected from the group consisting of chlorine atom-substituted biphenyl, chlorine atom-substituted naphthalene, chlorine atom-substituted fluorene and chlorine atom- Compounds are illustrated.

&Lt; Resin Separator &

The resin separator may be any film that can electrically insulate the positive electrode from the negative electrode and also allow lithium ions to permeate, and a porous polymer film is preferably used.

As the separator, for example, a porous film made of polyolefin such as a PP (polypropylene) porous film, a PE (polyethylene) porous film, or a laminated porous film of PP (polypropylene) .

<Exterior>

As the external body, known ones can be used.

As the type of the secondary battery, there are a cylindrical type, a coin type, a square type, a film type, and the like, and an external body can be selected according to a desired type.

Example

Examples and Comparative Examples according to the present invention will be described.

(Examples 1 to 9 and Comparative Examples 1 to 5)

&Lt; Positive electrode active material &

As the positive electrode active material, a ternary lithium complex oxide represented by the following formula was used.

_{LiMn 1/3 Co 1/3} Ni 1/3 O 2

&Lt; Preparation of positive electrode &

The above positive electrode active material, acetylene black (HS-100 manufactured by DENKI KAGAKU KOGYO KABUSHIKI KAISHA), which is a conductive agent, and a binder such as N-methyl-2-pyrrolidone [manufactured by Wako Pure Chemical Industries, Ltd.] PVDF (KF Polymer # 1120, manufactured by Kureha Co., Ltd.) was mixed at 90/6/4 (mass ratio) to obtain a slurry.

The slurry was coated on aluminum foil as a current collector by the doctor blade method, dried at 150 DEG C for 30 minutes, and pressed using a press machine to obtain a positive electrode. The positive electrode was applied in an amount of 10 mg / cm 2 and a thickness of 50 탆.

<Negative electrode>

As the negative electrode active material, graphite was used.

The negative electrode active material, the modified styrene-butadiene copolymer latex (SBR) as a binder, and carboxymethyl cellulose Na salt (CMC), which is a thickener, were mixed at a ratio of 98/1/1 (by mass ratio) To obtain a slurry.

The slurry was coated on a copper foil as a current collector by a doctor blade method, dried at 150 DEG C for 30 minutes, and pressed by a press machine to obtain a negative electrode. The negative electrode was applied in an amount of 5 mg / cm 2 and a thickness of 70 탆.

&Lt; Resin Separator &

A 20 占 퐉 -thick commercially available separator containing a porous film made of PE (polyethylene) was prepared.

&Lt; Porous heat-resistant layer (HRL layer) &gt;

In Comparative Example 1, the porous heat-resistant layer (HRL layer) was not used.

In Examples 1 to 9 and Comparative Examples 2 to 4, a porous heat-resistant layer (HRL layer) was used and an insulating inorganic filler shown in Table 1 was used. The average particle diameters of the insulating inorganic fillers used were all 8 to 10 mu m.

In Examples 6 to 9, as the insulating inorganic filler, the surface of the non-proton conductive ceramics used in Comparative Examples 1 to 3 was coated with a proton conductive ceramic.

In Example 6, at least a part of the surface of the non-proton conductive ceramic was coated with a proton conductive ceramic as described below.

Initially, EDTA was dissolved in ammonia water. To this solution, cerium acetate and ethylene glycol as a stabilizer were added and heated to dissolve.

Then, barium acetate was added and again heated to dissolve.

The resulting precursor solution was concentrated to obtain a 0.45 mol / L BaCeO ₃ precursor slurry. This precursor slurry was sprayed onto Al ₂ O ₃ particles and dried at 100 ° C for 5 minutes. Thereafter, it was baked at 1200 ° C for 2 hours, and the surface of the Al ₂ O ₃ particles was covered with a BaCeO ₃ film.

Observation with a scanning electron microscope (SEM) revealed that the thickness of the BaCeO ₃ film was 0.75 탆, and that the entire surface of the Al ₂ O ₃ particle was well covered with the BaCeO ₃ film.

Also in Examples 7 to 9, the surface of the non-proton conductive ceramics was coated with a proton conductive ceramic by using acetic acid salt as a precursor in the same manner as in Example 6. [

In all examples, acrylic rubber was used as the binder. The mass ratio of the insulating inorganic filler to the acrylic rubber was 90:10 (mass ratio). The thickness of the porous heat-resistant layer (HRL layer) was 5 mu m.

<Non-aqueous electrolyte>

A mixed solution of ethylene carbonate (EC) / dimethyl carbonate (DMC) / ethyl methyl carbonate = 3/3/4 (volume ratio) was used as a solvent and LiPF ₆ , a lithium salt as an electrolyte, And 2% by mass of cyclohexylbenzene (CHB) was dissolved as an overcharge preventing agent to prepare a nonaqueous electrolytic solution.

&Lt; Preparation of lithium ion secondary battery &gt;

In Comparative Example 1, the above positive electrode, negative electrode and resin separator were laminated. A film-type (laminate-type) lithium ion secondary battery was produced by using this laminate, the non-aqueous electrolyte, and the film sheath by a known method.

In Examples 1 to 9 and Comparative Examples 2 to 4, the positive electrode, the negative electrode, the resin separator and the porous heat-resistant layer (HRL layer) were laminated as shown in Fig. A film-type (laminate-type) lithium ion secondary battery was produced by using this laminate, the non-aqueous electrolyte, and the film sheath by a known method.

<Overcharge Test>

The preliminary experiment and the lithium ion secondary battery obtained in Example 1 were subjected to an overcharge test.

The amount of gas generated when the battery was once overcharged under conditions of 25 ° C, 1C, and a charging voltage of 4.6V was determined by the buoyancy method (Archimedes method). Before and after overcharging, a film-type (laminate-type) lithium ion secondary battery was immersed in water to determine the volume from buoyancy, and the amount of change in volume before and after overcharging was obtained as the amount of gas generation. This gas generation amount can be regarded as the hydrogen gas generation amount.

The results are shown in Table 1.

From the comparison of Comparative Example 1 and Comparative Examples 2 to 4, it was found that the use of the porous heat-resistant layer (HRL layer) using the insulating inorganic filler including the non-proton conductive ceramic greatly reduced the amount of hydrogen gas generation.

As a result of comparison between the comparative examples 2 to 4 and the examples 1 to 9, it was found that by using the proton conductive ceramic or the non-proton conductive ceramic coated with the proton conductive ceramic as the insulating inorganic filler of the porous heat resistant layer (HRL layer) It was found that the gas generation amount can be increased to a level close to that of Comparative Example 1 in which there is no porous heat-resistant layer (HRL layer). In particular, in Example 5 using a ceramic with addition of Y to BaCeO _3, carried out with the BaCeO ₃ than in Example 1 could increase the hydrogen gas production.

The nonaqueous electrolyte secondary battery of the present invention can be preferably applied to a plug-in hybrid vehicle (PHV) or a lithium ion secondary battery mounted on an electric vehicle (EV).

1: Non-aqueous electrolyte secondary battery
11: Exterior
12: Terminal
13: Current interruption mechanism
20:
21: positive
22: negative electrode
23: Resin Separator
24: Porous heat-resistant layer (HRL layer)

Claims (6)

A nonaqueous electrolyte secondary battery comprising: a positive electrode; a negative electrode; a porous heat-resistant layer disposed between the positive electrode and the negative electrode and including an insulating inorganic filler and a binder; And a current interrupting mechanism for shutting off the charging when the internal pressure of the battery becomes equal to or higher than a predetermined value,
At least a part of the insulating inorganic filler of the porous heat-resistant layer is constituted by a proton conductive ceramic,
Wherein the proton conductive ceramic comprises at least one metal oxide represented by the following formula (1).
&Lt; Formula 1 >

(Wherein A is at least one of Ba and Sr, B is at least one of Ce and Sr, C is at least one optional additive element, 0? X <1, a? 0) The method according to claim 1,
Wherein at least a part of the surface of the insulating inorganic filler is the proton conductive ceramic. The method according to claim 1,
Wherein the proton conductive ceramic comprises at least one metal oxide represented by the following formula (1a).
<Formula 1a>

(Wherein A is at least one of Ba and Sr, B is at least one of Ce and Sr, C is at least one of Y and Yb, 0 &lt; x &lt; The method of claim 3,
x is 0.01 to 0.5. 5. The method according to any one of claims 1 to 4,
A nonaqueous electrolyte secondary battery, which is a lithium ion secondary battery. delete

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